PROJECT SUMMARY Sugars, which are present naturally in some tobacco types and are also added to cigarette tobacco filler as additives, are not included in the FDA list of harmful and potentially harmful constituents (HPHC). Existing research data suggests that sugars in tobacco filler may contribute to the harmful properties of cigarettes in three critical ways: by enhancing smoke palatability and appeal and, as precursors to aldehydes and furans in the smoke, by increasing smoke toxicity and carcinogenicity and potentially addictiveness. Therefore, sugars are potentially the most versatile key constituents contributing to the smoking-associated morbidity and mortality. However, there is lack of robust quantitative data on the relationship between tobacco sugar content and relevant toxicant yields in U.S. commercial cigarettes, and the associated user exposures, behaviors, and cigarette appeal. In this study, we will leverage our combined expertise in tobacco chemistry, epidemiology, and human trials assessing biomarkers and behavioral and subjective measures, to address these key knowledge gaps. In Aim 1, we will use stable isotope-labeled sugars added to a commercial cigarette that is low in sugars and will analyze the dose-dependent formation of correspondingly labeled pyrolysis products in the smoke of this cigarette. to characterize the impact of sugars in the filler of U.S. cigarettes on the relevant chemical profile of cigarette smoke. We will also analyze the impact of sugar content on the levels of nicotine and tobacco-specific nitrosamines (TSNA) in the smoke. In Aim 2, we will analyze sugars in U.S. commercial cigarettes and use PATH biomarker data to investigate the impact of sugar content in cigarette tobacco on toxicant and carcinogen intake in U.S. smokers. In Aim 3, we will investigate the impact of sugar content in cigarette tobacco on cigarette abuse liability and appeal by conducting a laboratory study in which smokers will assess study cigarettes with differing levels of sugars in a laboratory setting. The overall goal of this proposal is to provide the FDA with the scientific basis to determine whether sugars should be added to HPHC list and whether their levels in tobacco products should be regulated.